48 THE DEVELOPMENT OF THE SALIV.VRY GL.AJS'US IX M-\N" 



involves its trunk and extends along its branches into the tongue. 

 The lingual crossing is a classic landmark in this region, which can 

 be rendered more precise by limiting its application to the libers of 

 the nerve and to the lingual sulcus, in which sense it is used in the 

 descriptions of the Columbia embryos. In passing it may be noted 

 that the relation of a gland to the Ungual ner\e in the adult is of 

 no deeper morphological significance than any other topographical 

 relation, though it has imprinted itself upon the nomenclature of this 

 region in comparative anatomy. Glands, like other structures, are 

 more profitably compared upon the basis of their origin, and should 

 be referred to the sulcus from which their anlages are derived, irre- 

 spective of their ultimate size and the length of duct they may attain, 

 on which factors of growth their topographical situation will secon- 

 darily depend. 



The findings in the indi\idual embrj-os may now be considered. 

 Here, again, the series is arranged on the basis of the development of 

 the glands ; chronolog}" is not stricth^ adhered to. 



1. Sudler. " Embrjo CLX. X.B. 10.5. \'.B. 11. Probable age 5 

 weeks. In his seventh figure there is a small, almost semicircular, pro- 

 jection from the oral epitheUum ventrad from a point below the anterior 

 extremity of the first pouch. The ridge from which it projects is con- 

 tinued caudad into the lateral border of the pharj-nx. The figure 

 suggests the early anlage of the submaxillary as it occurs in the cat 

 and the pig. It is not referred to in the text. 



2. Hammar. Embrj'o of 13.2 millimeters length. The floor of 

 the alveoUngual region shows a ridgelike thickening of the epitheUum, 

 which increases in height as it is followed caudad, and terminates 

 abruptly at about the middle of the sagittal length of the gutter. 

 The anlage is thickened in its caudal sections. 



This description would lead us to conceive the anlage as ha\-ing 

 the outUne of a right triangle in lateral \-iew, the hj-pothenuse and 

 shorter leg free, the base attached to the Ungual sulcus. The thicken- 

 ing in the caudal sections would indicate the beginning of active 

 proUferation preparatory- to the estabUshment of a free-growing sprout. 



3. His. Embrj-o Sch. 2, of 13.8 milUmeters length. The caudal 

 end of the lingual sulcus runs out into a bUnd epitheUal tube, the 

 anlage of the submaxiUarj^ gland {Aimt. mensch. Emb. Ill, Fig. 64). 



